A common feature of explosive ordnance is that it includes an explosive charge encased within a warhead. The warhead may be self-propelled, as the payload of a missile or rocket-propelled grenade (RPG), or it may be ballistic, as the payload of a mortar round, shell or air-to-ground bomb. Such explosive ordnance creates destruction and injury in two principal ways.
First, when detonated, the explosive charge creates a heated volume of gas and plasma that expands rapidly and disintegrates the warhead in which it is contained. Pieces of the disintegrated warhead create high-velocity shrapnel that may impact and damage surrounding structures, including vehicles, and personnel. Stationary structures may be hardened to protect against the damage caused by shrapnel. Protective armor may be applied to vehicles to lessen the damage caused by shrapnel, but such armor adds to the weight of the vehicle, which may negatively affect its performance. Body armor may be worn by individuals, but is less effective because such armor typically leaves portions of the individual, such as the head, arms and legs, unprotected.
Second, detonation of the explosive charge creates an expanding volume of hot gases and heated plasma caused by rapid combustion of the explosive charge. The outer boundary of the expanding volume of hot gases and plasma forms a pressure shock wave. Depending upon the energy released by the detonation of the explosive charge of the warhead, this shock wave may contain sufficient energy to severely damage adjacent structures, including vehicles, and cause injury or death to personnel it impacts. Stationary structures may be hardened to withstand the energy imparted by such shock waves. Adding armor to vehicles is less effective, especially with respect to lighter vehicles, which cannot carry heavy armor. Personnel may be particularly vulnerable to high-energy shock waves caused by exploding ordnance. For example, a shock wave from an explosion may at a minimum damage a person's ear drums, and at higher energy levels, can cause a concussion resulting from a person's brain impacting his skull, or death.
Accordingly, there is a need to develop a countermeasure that can lessen the destructive effect of shock waves caused by exploding ordnance. Such countermeasures preferably should be capable of deployment on the order of milliseconds once explosive ordnance has detonated.